Process of melting steel-scrap.



ALBERT E. GREENE, OF CHICAGO, ILLINOIS.

PROCESS OF MELTING STEEIr-SCRAP.

No Drawing.

- To all whom it may concern:

Be it known that I, ALBERT E. GREENE,

citizen of the United States, residing atv Chicago, in the county ofCook and State of Illinois, have invented a certain new and usefulImprovement in Processes of Melt ing Steel-Scrap, of which the followingis afull, clear, concise, and exact description.

My present invention relates to processes of melting steel and alloys inelectric furnaces and more particularly in induction furnaces andprovides a means of melting steel scrap with practically no oxidation ofthe metal or formation of oxid slag, and

therefore in an essentially deoxidized condition. a

Heretofore in the melting of steel in electric furnaces of the arc,resistance or induction types, it has been found that an oxid slag formswith considerable rapidity both during adding scrap and when heating ormelting. As soon as any oxid has formed, it immediately attacks andcombines with such elements and oxids for which it has afinity and formsa slag with them either alone or with the aid of more oxygen.- Thus itis that in practically every case the silicon and manganese, and suchelements as vanadium, tatanium, etc., and the alloy elements in general,are ,very rapidly oxidized and I pass into the slag in the melting ofsteel scrap containing these valuable alloys. Also when" the oxids comein contactwith a lining of opposite chemical nature, they flux with itand eat it away rapidly.

My presentinvention provides -a means of melting scrap and preventingthe formation. of oxid slag, thereby not only saving both the iron andalso special alloys contained in the scrap, but also very greatlyeliminating wear and corrosion of the linmg, and furthermore avoidingthe presence of any slag in pouring metal from the furnace.

In one of its embodiments myinvention relates to the melting of highgrade steel.

scrap already and sulfur.

The primary feature of my invention consists in the use of a reducinggas forced into contact with the metal or forced into the suitably purein phosphorus furnace chamber in proximity to the metal Specification ofLetters 'Patent.

Patented May 30, 1916.

Application filed December 18, 1912. Serial No. 737,558.

To carry out my process in one of its modifications, I may use aninduction furnace and one method of carrying out my process in such afurnace will now be described.

A suflicient amount of molten iron or steel charge is provided in aninduction furnace to permit of the furnace taking power. Heducing gas,preferably from a producer, is then forced into the furnace chamberpreferably so that it burns from any openings out of the furnace chamberwith a small flame. In this way it is possible to make sure that thefurnace chamber is full of gas and that no oxidation will occur. Forpreventing oxidation, it is not essential to have a gas which will burn,since a gas with only a very limited amount of reducing compo,- nentswill prevent oxidation of metallic oxid slag, but it is preferable. Witha relatively a low per cent. of reducing agent and conseouently largerpro ortion of oxidizing component, such asC there occurs, of course,

a fairly rapid decarburization of the metal surface of'the metal isreducedby the action of the gas, and in' case the gas is not forcedthrough in suflicient quantity to do this, it is only necessary toincrease the amount of gas or the amount of reducing components thereinand preferably tgbdirect it against.

the metal surface on which the sla rests.

" The melting of manganese stee scrap is one case wheremy rocess maybeused to advantage. Hereto ore in melting manganese steel scrap in arcfurnaces or' induction furnaces one of the difiiculties met with isexcessive wear on the bottom and lining; and another difliculty is theloss of manganese and simultaneous relative increase in proportion ofcarbon, yielding a product unsuitable for commercial use. Both thesedifliculties I attribute to oxidation of the metal, especially themanganese, and I have avoided both of these difliculties by my rocessand without use of abasic slag, and, 1n fact, without any slag whatever.The ef-' fect of a relatively large proportion of CO is to preventincrease in the percentage of carbon in the steel and to causedecarburization of metal and lower said percentage.

I do not limit myself to carrying out this process in an inductionfurnace, but I find that results can be attained in an induction furnaceby. the use of gas in the melting of steel scrap which heretofore to myknowledge have not been attained and which make it possible to verymaterially increase the life of the furnace lining and to diminish thewear on the walls. There is practically no corrosion ofthe walls whenthe slag is absent.

An additonal feature of my invention consists in the melting of steelscrap, irrespective of its alloy constituents, in either anacid lined ora basic lined vessel. I find that when a reducing gas is used, whichwill prevent the formation of 'any oxid slag, that there is practicallyno tendency of the alloy elements associated with the iron or steel toslag with the lining of the furnace. This feature of my invention makesit possible to melt a charge-containing metallic elements of both acidand basic nature in the same vesselfor example, manganese-silicon steelin an acid lined vessel.

The composition ofthe gas may vary greatly. Where a composition of gasis desired that will reduce the metallic oxids and "prevent oxidation ofthe metal without mg component, thus causing, of course, de-"carburization of the metal. Such composit1on of gas is particularly wellsuited to melting of manganese steel and manganese iron alloys where itis desired to prevent increase or to actually decrease thepercentage of'carbon in the metal. In the melting of low carbon vanadium steel and thelike, according to the process of this invention, it is desirable toprevent excessive-oxidation of the carbon and consequent decarburizingof the metal, since'in such, event the content of carbon in the metalbecomes so low as to be a hindrance to the melting and handling of themetal. Where it is desired to prevent oxidation of carbon, as 'well asof the metallic elements, the gaseous compounds of oxygen, such as C0,,or H 0, must either be absent or else their effect must be neutralizedor counteracted by having them in small amount, or using a gascontaining hydrogen or else a gas containing suitable carbon such ascoke, it is possible to control the gas composition at will and theoxidation of carbon may be prevented in the above manner. Hydrogen inthe gas is especiallyserviceable in keeping thev metal composition veryconstant." An acid steel or. metal may be retained in a basic linedvessel without essential combination of the acid elements in the steelwith the basic elements in the lining. T attribute this to the fact thatthe reactions involved in slagging an acid element like silicon requiregenerally the combined influence of oxygen to oxidize the silicon andalso the influence of the other radical or oxid to form the slag. Thus,if

silicon cannot get enough oxygen to form oxide in the metal is entirelyavoided. In

this way the absorption of gas is reduced to a minimum, and it is foundthat metal ob.- tained by this process is exceedingly finegrained anddeoxidized. Furthermore, the saving in alloys which are originallypresent in the charge is an item of considerable importance,particularly in the remelting of such steels as silicon steel, vanadiumsteel, andthe'lika,

' The absence of slag is a great advantage in pouring metal directlyfromthe furnace into molds.

The term scrap as applied to steel is understood to mean any materialsuitable for remelting to make steel.

My process is also particularly applicable to the melting of ferrometals such as ferromanganese. By the use of this process for meltingferro-manganese in an induction furnace, the oxid slag which forms inthe absence ofa reducing gas is avoided and the corrosive action of suchoxid on the lining of the furnace is thereby eliminated. In this way itis possible to usea very much cheaper lining not only for melting ferroalloys, but also for the 'melting of steel fication and claims areunderstood to mean such agents as lime which are commonly added to formslag and which are not to be reduced into the metal, and these terms donot include scale or such oxids of the metals as enter with the scrapand are reduced during the melting process.

What I claim is:

"1. The process of melting alloys, which consists in heating the alloy,without the use of a slag, in an electric furnace, while maintaining inthe furnace both a reducing atmosphere and non-carburizing conditionswith respect, to the alloy.

2. The process of melting steel scrap, which consists in melting thescrap, without the use of a slag, in an electric furnace, whilemaintaining in the furnace both a reducing atmosphere andnon-carburizing conditions with respect to the molten product.

3. The method of electric furnace operation for the melting and heatingof metals,

which consists inmelting said metal, without the use of a slag, andmaintaining in the furnace a reducing atmosphere which prevents theformation of oxids of the metal, thereby preventing the formation ofslag compounds of metallic oxids with the lining material of thefurnace. 1

l. In the melting-of steel scrap in an electric furnace, the method ofminimizing the power consumption, which consists in avoidmg use ofslag-forming agents which would require to be heated and melted,meanwhile during melting reducing any oxids entermg as scale with thesteel by keeping a continually freshened reducmg atmosphere above themetal surface in the furnace chamber, and thus at all times maintainingdeoxidizing conditions.

5.. The method of melting steel containing manganese and saving themanganese' therein from oxidation, which consists in charging themanganese-containing. steel into a suitable furnace chamber, melting itthere with electric heat, avoiding the entrance of slag-forming fluxesinto the furnace with the steel, and meanwhile, during melting,maintaining the atmosphere in the chamber above the metal surfacecontinually reducing toward oxids of the metal and maintaining in thegas a considerable proportion of carbon dioxid.

6. The method of melting steel containing an alloying metal of an acidand of a basic nature, respectively, which consists in heating the steelwithout addition of slag-forming flux in an electric furnace, andpreventing the slagging of the alloying metals therein with the furnacelining by passing areducing gas through the furnace during the meltingoperation, and thereby continually maintaining above the metal surfacein the furnace a reducing atmosphere toward oxids of the alloyingmetals.

7 The method of melting steel scrap containing silicon and manganese tosave those metals in the melted steel, said method consisting incharging said steel scrap containing these alloying metals into anelectric furnace without entrance of slag-forming fluxes, and, whilemelting the metal therein, maintaining the atmosphere in the filrnacechamber above the surface of the metal continually reducing toward themetals being melted.

8. The process of melting manganese steel scrap and preventing loss ofmanganese by oxidation without the use of a slag, which consists inproviding a bath of steel in an electric furnace, melting themanganesecontaining steel thereinto without slag 10. In the melting ofmanganese iron alloys to save the manganese and control the carboncontent thereof, the process which consists in melting the alloy in anelectric furnace in the absence of slag-forming additions in anatmosphere reducing toward oxid of manganese, and, during the meltingoperation, passing through the furnace a current of gas wh1ch isreducing toward the metallic oxids and oxidizing toward the carbon ofthe charge.

11. 1n the melting of manganese steel scrap, the process which consistsin providn ing a bath of molten steel in an electric furnace free fromslag-forming agents, and. while supplying the heat electrically andmaintaining a reducing atmosphere, charging the manganese-containingsteel scra and melting the same while passing throng the furnace acurrent of gas having reduce j; 1 ing properties toward oxids of iron ormam ganesepresent anddecarburizing properties toward the metal.

12. In the melting of manganese steel scrap in an electric furnace, theprocess which consists in causing the scale entering a with the scrap toreact with the carbon therein'under the influence of electric heat and areducing atmosphere, avoiding slagthe deoxidation of the steel.

- 13. In the melting of manganese steel scrap containing silicon to savethe manganese and silicon therein, the process which consists in meltingsaid scrap in a basic lined electric furnace in a reducing atmospheremasses Without slag-forming additions, and, meanwhile, passing throughthe furnace a gas which has reducing action on any oxids of the metalspresent.

In Witness whereof, I hereunto subscribe my name this sixteenth day ofDecember,

v ALBERT E. GREENE. Witnesses:

MGCLELLAN YOUNG, GEORGE E. FOLK.

